Hack saw



A. MACRINI HACK SAW Filed March 5, 1923 YIIIIIIIIIII;

- l/vmvrok HLFREDFMHCRIH By A TTORNEVS WITNESSES Patented Apr. 28, 1925.

' UNITED STATES ALFRED FRED MACR INI, OF NEW YORK, N. Y.

HACK SAW.

Application filed March 3, 1823. Serial no. 622,623.

tion.

This inventionrelates to saws, and more particularly aims to provide a handle or a holder for replaceable saw blades, whereby a blade may be set inplace, or one blade substituted for another, or the tautness of a blade may be varied, or a blade may be set in any one of a plurality of cutting olanes in ever case ulckl and securel va y y and in a manner to facilitate rapid cutting and nnnmnze blade breakage or other damage. In the present case, the invention Wlll be illustrated and described as applied to anordinary hack saw as such an embodiment thereof is most advantageous.

It is fact Well appreciated, especially in the case of hack saws, that the inser tionor settingof a blade is a task of some annoyance and. often of considerable trouble, due to the fact that in hack saws as previously constructed, the end-shackles for the blades have an extremely impositive hold on the blade from the instant the same is hooked onto such shackles until the blade is finally tautened in place; that the slidearn rfor the outer blade shackle must have a certain toothed or ratchet adjustment on the main frame bar, in connection With the preliminary setting of which considerable judgment must be shown if the blade is immediately thereafter to be securely and rapidlytightened up with the tautness desired; that the ability to reproduce nicely a pre viously employed degree of blade-tautness is practically impossible; and that it is difficult if-not impossible to securely set the blade in a'plane at a predetermined angle to the plane ofsaid frame bar.

The prime object of the invention is to provide a novel type of saw-in which all the above disadvantages are overcome.

Animportant object of the invention is to provide a saw as just characterized, and

one in which the partsare rugged and longlived, and which saw shall also be exceedingly compact,'light in weight, and comparatively inexpensive to manufacture.

Various other objects and advantages of the invention will appear hereinafter, from the description of the hack saw embodi' ment illustratively shown in the accompanying drawing, in which drawing- Fig. 1 is a side elevation, partially broken away and partially in section, of said embodiment Fig. 2 is a transverse section, taken on the line 22 of Fig. l; and

Fig. 3 shows certain of the parts of Fig. 1, but some. of said parts being in section to show underlying parts,-the plane of such sections-being? indicated by the line of Fig. 2. I

Referring now to the structural details of the drawing, the frame of the sawincludes, as isconventional, a main bar 4, an integral offset fixed arm 5, and a sliding arm 6; and said frame has offset from the lower arm of dle'7. K i

Arms 5 and 6 ofgthe frame have movably mounted thereompreferably in line With handle 7, end-shackles 8 for engaging opposite ends of a familiar hack saw blade 9.

,An important feature of the present construction resides in the fact that the upper end of sliding arm 6 isnot intended toube placed in toothed or ratchet engagement with a part of main 4, but instead these parts 6 and carry a sliding bar, whereby a tautening pull on blade 9 toward handle 7, automatically and simultaneously actuates said bar, but otherwise the arm 6 is freely slidable along-the length of bar 4. SillU-h sliding bar includes an upper portion 6 for arm 6, which portion is forked t0 straddle bar 4 and provide spaced eXten sions (i above said bar in which may be set a cross pin 10 overlying a transverse groove 11- in the elongate sliding bar 12. Ithas been found that a pull of the kind just described on the lower end of arm 6 will lock the arm 6 in absolute fixation on bar 4 during maintenance of such pull. The sliding bar 12 is provided with a roughened thumb-rest 13, by means of which it has been found, on the other hand, arm 6 may he slid easily from end to end of bar 4 fixed arm 5 a rigid hanwhen. such pull on the blade isv released and the blade is disengaged from one or both of shackles 8. j p y In order to incorporate suitable means for thus pulling on blade 9 and so simultaneously tautening the same and locking arm 6 by the bar aforesaid, the following parts are provided: mounted in any suitable manner on the lower end of arm 6, the inner shackle 8 is slidably mounted on the saw frame parallel to the line of extension of main bar t and blade 9, by being carried in any suitable manner by a slide rod 1% set in a bore and normally urged toward outer shackle 8 by means of an expansile spring 16 also in said bore. Further, rod 14 has an offset stud or projection 17 extended substantially perpendicular to the plane of the saw frame and protruding beyond one of a pair of side brackets 18 which connect up with lower end of fixed arm and the contiguous end of handle '7. This pin, riding in a slot marked 18 in Fig. 1, serves to limit the sliding movements of rod 1%; and the pin may have an enlarged head as marked 19 in Fig. 1. A thumb lever 20 is pivoted as at 21, by means of the screw illustrated in Figs. 1 and 2, on the bracket 18 shown in Fig. 1; and this lever around its point of pivoting has an edge formed as a cam surface of which stud 17 is a follower.

There is also provided a resiliently impositive but entirely reliable locking means for the cam means just described, involving the combination of lever 20, stud 17 and spring 16, and particularly a concave surface 23 on cam member 20, such element 23 immediately adjoining cam surface 22. It will be readily understood that when lever 20 has been thumb-pulled in an anti-clockwise direction as viewed in Fig. 1 to tauten up blade 9 and lock arm 6 on bar 1- as shown in said Fig. 1., a slight further pull on the lever will cause the look just mentioned to function, at the instant concave surface 28 is snapped into hugging engagement against stud 17.

Another important feature of the present structure is the presence of means, in combination with the means above described, whereby a spiral adjustment of one shackle 8 is permitted relative to the other, and yet without causing any binding of stud 17 in slot 18. In this connection the following parts are provided. Outer shackle 8 terminates in a threaded shank 2a. This shank is set in a similarly threaded recess 25 in the lower end of arm 6. Intermediate such recess the arm is slotted across the plane of the frame to accommodate a nut 26 on shank 24. The other shackle 8 also has a similar shank, and said shank is spirally adjustable in a suitably tapped recess marked 27 in Fig. 3, and formed, as there shown, in the outer end of rod 14. Thus, by applying thumb pressure to rotate nut 26 in one direction or the other, the blade 9 may be conveniently given a very nice degree of taut-ness, or the shackles may be moved toward each other sulficiently to relieve too much stretch in the blade, irrespective of any resetting of lever With the outer shackle 820, once the same has been locked on stud 17 by means of the concave recess 2?.

Regarding the structure of the shackles themselves, means are incorporated whereby the ends of the blade will be sufiiciently securely held by the shackles, once the blade ends have been even loosely engaged with such shackles; thus to avoid the nuisance of having manually to hold each'blade end tight against its shackle while at the same time tautening the blade between the shackles. In the present case, each shackle includes an offset stud 28 for taking each of the usual apertures in the end of a blade; but contrary to the usual construction, these studs are conveniently perpendicular to the plane of the blade, and yet are effective to act as just described, due to the provision on each shackle of a lip 29 adapted to overlie an end edge portion of the blade adjacent to the usual aperture thereinv This simple device has been found to fully satisfy all practical requirements in attaining the object just stated.

In order, finally, to provide in a saw having the above described valuable operating features, means for permitting the plane of the blade to be set at any one of a great plurality of possible angles to the general plane of the saw frame, and thus to permit the blade to be set without interfering with any of the above referred to adjustments, the following parts are provided: Inner shackle 8 fixedly carries a disk enlargement- 30 provided around its periphery with eight or any suitable number of notches as illustrated, and preferably equidistant. These notches are desirably shaped to hug half the girth of a cylindrical pin 31 offset from the lower end of fixed arm 5 to extend in the general plane of the saw frame and hence perpendicular to the plane of the disk 30. It will be clear that according as the disk 30 is turned to dispose blade 9 in the plane desired relative to the plane of the saw frame, preparatory to actuating lever 20 and nut 26 or either of them to tauten and control the tightness of blade 9, such blade will be finally securely anchored in the plane desired when finally thus tautened.

It will thus be seen that there has been provided an embodiment of the invention, and one well adapted to attain all the various objects and advantages hereinabove expressed or suggested. The unique sliding feature of arm 6, particularly, which instantly does away with the previous unreliable or difiicult to adjust step-by-step adjustments, affords an instantaneously adjustable saw which will take any and all sizes of blades; whereas the sliding arm is absolutely securely locked whenever the selected blade is tautened to a working stretch, and solely by a single swing of lever 20. In addition, the degree oftautness of blade 9 may be very nicely and reliably varied, solely by giving nut 26 a few turns or a fraction of a turn. At no time during the blade-setting and adjusting operations just described, must the blade setter have to give thought to an accidental loss of blade 9, due to the simple but highly important blade-engaging structural features of the shackles.

i It should, however, be, stated in conclusion that while the illustrated example constitutes a practical embodiment of theinvention, the same, as above stated, is merely an example of one of the possible ways in which the invention may be carried out; and I do not limit myself strictly to the exact details herein shown, since, manifestly, the same may be considerably varied Withoutv departure from the spirit of the invention as defined in the appended claims. I claim: p 1.111 a saw having a frame, including a main bar, a handle unit capableof being at tached to the frame, said handleunit having a bore therein, a slidable rod in said bore, a spring in the bore back of the rod tending to force it out of the bore, the handle unit having a slot, a pin on the rod extending through said slot, a roller on the end of said pin, and a cam memberpivotally attached to the outer surface of the handle unit, a por tion of said'cam member engaging the roller whereby the position of the rod within the bore can be regulated.

2. In a saw having a frame, including a main bar, a handle unit capable of being attached to the frame, said handle unit having a bore therein, a slidable rod in said bore, a spring in the bore back of the rod tending to force it out of the bore, the handle unit having a slot, a pin 011 the rod extending through said slot, a roller on the end of said pin, and a cam member pivotally attached to the outer surface of the handle unit, a portion of said cam member engaging the roller whereby the position of the rod within the bore can be regulated, said cam surface having a plurality t. In a saw having a frame and a main bar, which comprises a handle unit attachable to the frame and having a bore therein, a slidable rod in said bore, a spring in the bore tending to force the rod out of the bore, cam means for adjusting the rod in any desired position, the rod having a threaded bore therein, a threaded shackle member adjustably mounted in said bore, a notched plate on the shackle member, and a pin on the handle member engageable in the notches to adjust the shackle unit in any desired. angular posit-ion with respect to the handle.

5. In a saw having a frame and a main bar, which comprises a handle unit attachable to the frame and having a bore therein, a slidable rod in said bore, a spring in the bore tending to force the rod out of the bore, cam means for adjusting the rod in any desired position, the rod having a threaded bore therein, a threaded shackle member adjustably mounted in said bore, a notched plate on the shackle member, a pin on the handle member engageable in the notches to adjust the shackle unit in any desired angular position with respect to the handle, a slidable bar mounted on the main bar and having a slot in its lower end and i a threaded bore, said bore and slot disposed at right angles to each other, a shackle member having a threaded stem in said bore, and a nut in said slot thrcadably engaged with said stem whereby the shackle member may be adjusted with respect to the lower end of the slide bar.

ALFRED FRED MAGRINI. 

